Runes are dropped from various sources in Diablo 4, but to begin collecting them, you must first complete the “Fundament of Faith” chapter in the Vessel of Hatred campaign. After that, you can farm them from a variety of in-game sources.

<h4>Guaranteed Sources of Runes:</h4>
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<li>Campaign Bosses: Defeating key bosses in the Vessel of Hatred campaign guarantees buy d4 runewords drops. However, you can only obtain Runes once per boss.</li>
<li>World Bosses: Killing world bosses ensures Rune drops, making them a reliable farming source.</li>
<li>Stronghold Clears: The first time you clear a Stronghold guarantees a Magic-quality Rune, but this only works if you&rsquo;re level 20 or above.</li>
<li>Kurast Undercity District: Runs with the Tribute of Harmony guarantee Rune drops if you have at least Attunement Rank 1.</li>
<li>Materials Caches: Reaching Rapport VIII with Aldkin unlocks access to Materials Caches in The Den, which contain Shattered Prisms, Gems, and Runes.</li>
</ol>
To learn more, you may want to check out this article on u4gm Diablo 4 Season 6: Best Upheaval Barbarian Build Guide